Gas turbine engines can be used to power aircraft, watercraft, power generators, and the like. Gas turbine engines typically include a compressor, a combustor, and a turbine. A fan or propeller may be used to draw air into the engine. The compressor compresses the air and delivers higher-pressure air to the combustor. In the combustor, fuel is mixed with the higher-pressure air and is ignited. Products of the combustion reaction in the combustor are directed into the turbine where work is extracted to drive the compressor and, sometimes, an output shaft. Left-over products of the combustion are exhausted out of the turbine and may provide thrust in some applications.
Where the turbomachinery is only intended to act as a genset, it may consist only of a turboshaft engine in which a motor is driven by an engine shaft. If the turbomachinery provides both propulsion and power, one or more generators may be mounted to an engine shaft.
Hybrid turbo electric propulsion systems may be used to power aircraft. In hybrid turbo electric aero-propulsion systems, a motor may be used in combination with a turbine engine to provide motive power to one or more fans or propellers. In distributed propulsion systems, the fans or propellers are placed at other locations around the aircraft, rather than being co-located with the engine. These distributed devices may be referred to as propulsors. The propulsors include a motor/generator which drives a fan. The fan may be used to provide forward thrust or reverse thrust (e.g., during landings). Additionally, the fan may be used to extract work from the airflow to provide electrical power. This may be useful, for example, during failure scenarios.
Thrust can be modulated by varying turbine speed, fan pitch, guide vane angles, nozzle/inlet areas, and/or other operating parameters.